The objective of this study is to develop and evaluate a prototype health service utilization review system. A system will be designed for reviewing a patient's use of hospital resources while the patient is still hospitalized, such that this concurrent review system complements a retrospective review system. The application of decision analysis, a set of techniques from operations research, will be developed and tested for use in deciding on the appropriate use of hospital resources. The prototype system will be developed and evaluated in two hospitals. The duration of the study will be three years. In the first six months, the concurrent utilization review system will be designed and installed in two hospitals. During the following 12 months, a series of studies will be conducted to develop the techniques necessary to provide the concurrent utilization review systems in these hospitals with solutions to their problems, including techniques for predicting which patients to review in detail, techniques for developing criteria in medical staff meetings, techniques for selecting among alternative locations for patients, and techniques for evaluating the review system on an ongoing basis. During the next six months, the techniques will be made operational in two hospitals. In the remaining 12 months, the techniques and review system will be evaluated.